Emily has taken 6 tests and her average score so far is 80. If she gets 100, a perfect score, on the remaining 4 tests, what will her new average be?
If she gets 100 on the remaining tests, the sum of her scores will be $6 \cdot 80 + 4 \cdot 100 = 880$ Her overall average will then be $880 \div 10 = 88$.